Drawing, the practice behind human visual and artistic expression, can essentially be defined as an iterative process. It starts from an initial outline, with just a few strokes that specify the spatial arrangement and overall layout, and is then gradually refined and embellished with color, depth and richness, until a vivid picture eventually emerges. These initial schematic sketches can serve as an abstract scene representation that is very concise, yet highly expressive: several lines are enough to delineate three dimensional structures, account for perspective and proportion, convey shapes and geometry, and even imply semantic information [1]}, [2]}, [3]}. A large body of research in psychology highlights the importance of sketching in stimulating creative discovery [4]}, [5]}, fostering cognitive development [6]}, and facilitating problem solving [7]}, [8]}. In fact, a large variety of generative and RL tasks either in the visual [9]}, textual [10]}, [11]} or symbolic modalities [12]}, can benefit from the same strategy – prepare a high-level plan first, and then carry out the details.
